VBAC—The "Approach to Counseling and Management" Case File

VBAC—The "Approach to Counseling and Management" Case File

Eugene C. Toy, MD, Edward Yeomans, MD, Linda Fonseca, MD, Joseph M. Ernest, MD

Case 5

A 32-year-old G4P3003 Hispanic female with no prenatal care presents to the hospital at 40 weeks stating that her membranes ruptured the day before and her contractions began about 8 hours prior to this admission. For the past 4 hours she has noted progressively severe pain and decreased fetal movement. A recent immigrant from El Salvador, her primary language is Spanish. She is a single mother with three children, ages 12, 10, and 1 year old. She states that her first delivery was by cesarean section because she never went into labor, second was a normal vaginal delivery, and third was a cesarean section at a public hospital in San Antonio, Texas when she “...went into labor early and the baby was in the wrong position.” She states that she did not want second cesarean because her first one had been complicated by a wound infection that required 2 months of packing and cleaning.

She tells you that she is very worried about having another cesarean section, but also wants to do whatever is the safest for her fetus. She denies diabetes, hypertension, or any chronic medical illnesses. She does not smoke, drink, or use illicit drugs. Both of her parents are obese with diabetes and hypertension.

On physical examination she is in moderate distress with frequent contractions and complains that her right shoulder hurts. The maternal heart rate is 140 beats per minute (bpm). Her blood pressure is 80/40 mm Hg. Her temperature is normal. She is obese with a BMI of 35 kg/m2. Her fundal height is difficult to measure, but appears near term. Her abdomen is mildly tender in all quadrants. The nurse reports that fetal heart tones by external Doppler are 140 bpm with absent variability and no accelerations. On pelvic examination she is 8 cm dilated, 90% effaced, and the fetal vertex is floating above the pelvic inlet.

➤ What is the differential diagnosis?

➤ What is the most likely diagnosis?

➤ What are your next steps in caring for this patient?

ANSWERS TO CASE 5:

VBAC—The “Approach to Counseling and Management”

Summary: This is a patient with two prior cesareans, one prior vaginal delivery, nonrepetitive indications for the prior cesareans, an unknown scar(s), an inter-pregnancy interval of only 30 weeks and current risk factors for macrosomia. Her presentation suggests hemodynamic instability and possible fetal compromise.

➤ Differential diagnosis: Uterine rupture, abruptio placenta, chorioamnionitis with sepsis, pyelonephritis, appendicitis, cholecystitis or other intra-abdominal acute processes.

➤ Most likely diagnosis: Uterine rupture.

➤ Next steps: This is a life-threatening emergency for both, the mother and the fetus. Quickly notify essential personnel such as anesthesia, operating room staff, blood bank, and laboratory services. Immediately obtain large bore IV access. Simultaneously obtain blood for cross match and coagulation studies with one red-top tube taped to a wall to observe for clotting. Resuscitation with volume repletion is important while assessing the mother and determining fetal status. As the fetal heart rate is the same as the mother’s, a quick ultrasound to assess fetal viability should be obtained but should not delay the next steps. While continuing to resuscitate the mother, the patient should be immediately moved to the operating room as surgical management is imperative at this point even if the fetus is already dead. Usually, a general anesthetic is indicated, as this clinical situation does not permit the time required for a regional anesthetic.

ANALYSIS

Objectives

1. Be familiar with historical, antenatal, and intrapartum factors that influence the likelihood of success if attempting a trial of labor.
2. Be familiar with historical, antenatal, and intrapartum factors that influence one’s risk of uterine rupture during a trial of labor.
3. Be able to counsel patients regarding the maternal and newborn outcomes associated with (1) trial of labor, (2) elective repeat cesarean, and (3) uterine rupture in labor.
4. Describe the most common signs of intrapartum uterine rupture.
5. Describe the intrapartum and operative management of uterine rupture.

Considerations

The most recent report of births from the National Center for Health Statistics shows that the VBAC (vaginal birth after cesarean) rate in the United States continues to decline and is now less than 10%.1 While the reasons for this are multiple, an unavoidable effect is that women who plan larger families will increasingly face the specter of multiple cesarean sections over a reproductive lifetime. In light of the individual and societal consequences, appropriate counseling about primary and repeat cesarean delivery is essential.

The counseling and management for vaginal birth after a previous cesarean section presents a number of opportunities and challenges. As much as possible, the counseling should be specific for the individual patient. Information gained from a thorough review of the events surrounding the previous cesarean section(s) may inform a particular patient’s likelihood of successful VBAC as well as her risk of uterine rupture. Similarly, characteristics of the current pregnancy and labor may also modify the chances of success or the likelihood of uterine rupture. Consequently, VBAC counseling is not necessarily a one-time event and may need to be readdressed as circumstances of the current pregnancy change. In addition to an objective description of the maternal and newborn outcomes associated with a successful or failed trial of labor, patients should also be informed of the maternal and fetal consequences of uterine rupture. Finally, if uterine rupture does occur, prompt recognition and management are vital to optimize outcomes for both the mother and her fetus.

APPROACH TO

Vaginal Birth After Cesarean: The “Approach to Counseling and Management”

FACTORS AFFECTING THE LIKELIHOOD OF 

SUCCESS OF A TRIAL OF LABOR

Large observational studies from a wide range of practice environments suggest that the overall likelihood of success with an attempted VBAC is between 60% and 80%.2,3 Studies with more selective criteria for VBAC candidates usually report success rates of about 75%, while studies with more liberal inclusion criteria report success rates closer to 60%. The two most important factors in determining a particular patient’s chances of success are a history of a prior vaginal birth and the indication for the previous cesarean delivery.4-6 The chance of a successful VBAC with a prior vaginal birth is generally reported as 85% compared to 60% without such a history. Similarly, the chance of success if the prior cesarean was performed for a nonrepetitive indication such as malpresentation or a nonreassuring fetal heart rate tracing also approaches 80% to 85%. Women whose previous cesarean section was performed for dystocia generally have a success rate closer 50% to 60%. Other factors associated with a lower likelihood of success include an unfavorable cervix, need for induction of labor, maternal obesity (BMI > 30), fetal weight greater than 4000 g, fetal weight more than 500 g greater than the previous newborn, maternal diabetes, and a maternal age greater than 35 years. Several investigators have tried to combine these and other predictive factors by creating sophisticated prediction models to identify an individual patient’s likelihood of success. Unfortunately, none of these models has proven clinically useful when applied prospectively. With the possible exception of the negative prognostic effect of a previous cesarean for second-stage arrest, none of the previously mentioned factors, alone or in combination, will reliably predict a success rate below 50%.

Factors Affecting the Risk of Uterine Rupture

The likelihood of a successful VBAC may influence an individual patient’s decision to undergo a trial of labor, but the risk of uterine rupture usually weighs more significantly in that decision. Large prospective cohort studies and a large meta-analysis suggest that the overall risk of uterine rupture during a trial of labor is about 0.6% to 0.7%.2,7 When counseling an individual patient about the risk of uterine rupture, it is important to identify factors that may predict a higher risk of uterine rupture. These include the conduct and circumstances of the prior cesarean(s), antenatal factors, and intrapartum factors.

First among these is a careful review of the operation reports from prior cesarean sections or other uterine surgeries. Prior classical uterine incisions, “T-shaped” incisions, or large resections of intramural fibroids may be associated with rupture rates as high as 6% or 8% and should be considered contraindications to a trial of labor.

Other historical factors influencing the risk of uterine rupture include a prior vaginal delivery, the number of previous cesareans, the technique of the previous uterine closure, endometritis following the prior cesarean, and the inter-pregnancy interval.8,9 A prior vaginal delivery reduces the likelihood of uterine rupture in a subsequent trial of labor by as much as 60%.5,10 Although the number of previous cesarean sections is important, it may not have as much of an effect on the risk of rupture as early studies had indicated. Early small retrospective cohort studies suggested that the risk of uterine rupture with two prior low-transverse cesarean sections was between 2.3% and 3.7% or about four times that of a patient with only one prior cesarean.11 On the basis of studies that were available at that time, the American College of Obstetricians and Gynecologists published a practice bulletin suggesting that women with two prior cesarean deliveries were not appropriate candidates for a trial of labor unless they had had a previous vaginal delivery. However, more recent data from a larger prospective cohort study suggest that the risk of uterine rupture with two prior cesareans is not that different than with only one (0.9% vs 0.7%).12 Several retrospective cohort studies and one secondary analysis of a clinical trial have examined the relationship between technique of single- versus double-layer and the subsequent risk of uterine rupture during a trial of labor.13-15 Although not all of the studies are consistent, on balance the results suggest an increased risk of rupture with a single-layer closure. While these reports do not preclude a trial of labor after a single-layer closure, the information may support two-layer closure at the time of cesarean section for women who might consider a trial of labor in the future. Finally, a review of prior inpatient records may also be informative. The authors of a retrospective cohort study reported that post-cesarean fever was associated with a fourfold increase in the risk of uterine rupture in a subsequent trial of labor.16

In addition to the conduct and circumstances surrounding the prior cesarean delivery, clinicians should also consider factors associated with the current pregnancy when counseling patients regarding the risks and benefits of a trial of labor. Maternal age greater than 30 years has been suggested as a risk factor for uterine rupture, but this has not been observed in large studies using statistical modalities to control for other factors. Several authors have reported that a short inter-pregnancy interval is associated with an increased risk of rupture, but there is no uniform agreement as to the critical time. One of the larger studies demonstrated odds ratios for uterine rupture of 2.6 and 4.8 for inter-delivery intervals of less than 24 months and less than 12 months, respectively.17 Prematurity in the current pregnancy appears to be associated with a decreased risk of uterine rupture. Surprisingly, while fetal macrosomia may decrease the chance of a successful VBAC, it is not associated with an increased risk of uterine rupture.18

Lastly, the relationships between intrapartum factors and the risk of uterine rupture are complex. Most, but not all, large observational studies demonstrate an increase in the risk of uterine rupture with induction of labor with an absolute risk of 1% to 3% regardless of the method of induction.2 Reports of studies examining the relationship between methods of induction of labor and the risk of uterine rupture have produced conflicting results. One large observational study suggested a significant risk of rupture with any use of prostaglandins compared to induction with oxytocin alone while two larger studies showed either no similar risk or only a very small incremental risk in uterine rupture.2,19,20 Nonetheless, at this time the American College of Obstetricians and Gynecologists recommends against the use of prostaglandins for the induction of labor in third-trimester patients with a previous cesarean delivery.

Maternal and Newborn Outcomes With Trial of Labor Versus Elective Repeat Cesarean

When counseling patients about VBAC, it is also important to inform them of the maternal and newborn outcomes associated with the different options. At this time, the best estimates of maternal and newborn outcomes are those

Table 5–1 MATERNAL OUTCOMES WITH TRIAL OF LABOR VERSUS ELECTIVE REPEAT CESAREAN SECTION
OUTCOME	TRIAL OF LABOR (%)	REPEAT CESAREAN (%)	ODDS RATIO	P VALUE
Hysterectomy	0.20	0.30	0.77	.22
Thromboembolic disease	0.04	0.10	0.62	.32
Transfusion	1.7	1.0	1.71	<.001
Endometritis	2.9	1.8	1.62	<.001
Maternal death	0.02	0.04	0.38	.21
Other morbidity	0.4	0.3	1.09	.66
Any of the above	5.5	3.6	1.56	<.001

Reproduced,with permission, from Landon MB,Hauth JC, Leveno KJ, et al.Maternal and perinatal

outcomes associated with a trial of labor after prior cesarean delivery. N Eng J Med. 2004;351:2581-2589.

Copyright © 2004 Massachusetts Medical Society. All rights reserved.

reported from the large, multicenter prospective cohort study conducted by the NICHD Maternal-Fetal Medicine Units (MFMU) research network.2 This was a prospective cohort study with 17,898 trials of labor and 15,801 elective repeat cesarean sections all reported with strict ascertainment rules. Maternal outcomes are shown in Table 5–1 and fetal outcomes are shown in Table 5–2. It is important to discuss both the absolute and the relative risks of these adverse outcomes in order to avoid bias. Often, patients will ask, “What happens if the uterus does rupture?” Here again, the results of the MFMU report are helpful. Rounding to numbers that are easier for counseling, if the uterus ruptures one can expect 1/50 infants to die, 1/20 to have hypoxic ischemic encephalopathy, 1/3 to have a pH less than 7.0, and about half to be admitted to the neonatal intensive care unit. At this point, it is often helpful to return to the previous estimates of absolute risks associated with either a trial of labor or elective repeat cesarean. Conversations concerning these discussions with the patient should be documented in the medical record and at the time of informed consent.

Signs of Uterine Rupture

A number of studies have reported the signs and symptoms of uterine rupture during a trial of labor. The most common sign is an abnormal fetal heart rate tracing, usually prolonged, persistent fetal bradycardia. Less common signs

Table 5–2 PERINATAL OUTCOMES WITH TRIAL OF LABOR VERSUS ELECTIVE REPEAT CESAREAN DELIVERY
OUTCOME	TRIAL OF LABOR (%)	REPEAT CESAREAN (%)	ODDS RATIO	P VALUE
Stillbirth 37-38	0.40	0.10	2.93	.008
Stillbirth ≥ 39	0.20	0.10	2.7	.07
Intrapartum 37-38	0.02	0	—	.43
Intrapartum ≥ 39	0.01	0	—	1.00
HIE	0.08	0	—	<.001
Neonatal death	0.08	0.05	1.82	.19
Any of above	0.38	0.13	2.9	<.001

Reproduced,with permission, from Landon MB,Hauth JC, Leveno KJ, et al.Maternal and perinatal

outcomes associated with a trial of labor after prior cesarean delivery. N Eng J Med. 2004;351:2581-2589.

Copyright © 2004 Massachusetts Medical Society. All rights reserved.

include abdominal pain, loss of fetal station, gross hematuria, cessation of uterine contractions, vaginal bleeding, or signs of massive intra-abdominal bleeding with shock as in the current case scenario.

Management of Uterine Rupture

Suspected intrapartum uterine rupture is a true surgical emergency with two patients at risk. In the present scenario, the mother needs volume; initially two large-bore intravenous lines should be placed and isotonic crystalloids infused, but given her degree of shock she will almost certainly require blood transfusion. With severe maternal tachycardia and this degree of systolic hypotension, the patient has probably lost at least 30% to 40% of her blood volume. In this situation, O-negative or type specific non–cross-matched blood should be released for possible use until cross-matched blood is available. The risks of a hemolytic transfusion reaction from O-negative or type specific, non–cross-matched blood are small and greatly outweighed by the need for red cells in this situation. Importantly, vasopressors play a limited role in the management of massive hemorrhage. Recent evidence from a large, multicenter, prospective cohort study of patients with hemorrhagic shock from blunt trauma shows that when compared to early crystalloid resuscitation, the use of vasopressors of any type is associated with a twofold increased risk of mortality at both 12 and 24 hours.21 The use of vasopressors in the setting of massive hemorrhage should be limited to those patients who are not responding despite aggressive volume resuscitation while moving toward definitive surgical control.

Surgical management of suspected uterine rupture requires immediate laparotomy, delivery of the fetus, and exploration of the extent of injury to the uterus and surrounding organs. However, even with heroic efforts at emergency cesarean, fetal deaths or injuries cannot always be prevented even with delivery times of less than 10 minutes. The location and extent of the uterine injury will dictate the appropriate surgical management, but hysterectomy is not necessarily required. Because uterine ruptures are often irregular and do not always involve the previous uterine scar, it is important to thoroughly explore the posterior and lateral aspects of the uterus, the uterine vasculature, and the bladder and surrounding organs.

Comprehension Questions

5.1 Which of the following is associated with the greatest likelihood of a successful vaginal birth after a previous cesarean section?

A. Prior cesarean performed due to arrest of dilation at 6 cm

B. Prior cesarean performed for arrest of descent in the second stage

C. Prior cesarean section for an unknown reason

D. Prior cesarean section for breech presentation

5.2 Which of the following is least likely to be associated with an increased risk of uterine rupture during a trial of labor?

A. An inter-delivery interval of greater than 2 years

B. A history of prolonged fever following the prior cesarean section

C. A single-layer closure of the prior cesarean hysterotomy

D. Two prior cesarean sections with no prior vaginal delivery

5.3 Which of the following is the most common sign of an intrapartum uterine rupture?

A. Loss of fetal station

B. Maternal pain

C. Loss of contractions

D. Maternal shock

E. Sudden onset, prolonged fetal bradycardia

5.4 The overall risk of a serious complication defined by hysterectomy, neonatal death, or hypoxic ischemic encephalopathy from an attempted vaginal delivery is closest to which of the following?

A. 1/10

B. 1/100

C. 1/1000

D. 1/10,000

ANSWERS

5.1 D. Estimates of the likelihood of successful VBAC based on the indication for the prior cesarean are as follows: (1) prior cesarean for breech—80% to 85%, (2) prior cesarean for nonreassuring fetal heart rate tracing—80% to 85%, and (3) prior cesarean for dystocia in the active phase—50% to 65%.

5.2 A. Although various authors have defined a short inter-pregnancy or inter-delivery differently, most of the literature suggests that an interdelivery interval greater than 18 or 24 months is associated with a decreased risk of uterine rupture.

5.3 E. Although all of the choices should be of concern and raise the concern for uterine rupture during a trial of labor, multiple authors have demonstrated that the most common sign is an abnormal fetal heart rate tracing, usually prolonged bradycardia. Serious variables and late decelerations have also been described and are of particular concern when followed by the onset of prolonged bradycardia.

5.4 C. The authors writing for the NICHD MFMU research network prospective cohort study group suggested a risk of neonatal death or hypoxic ischemic encephalopathy of 1 in 2000 trials of labor. An analysis from the Agency for Healthcare Research and Quality (AHRQ) suggests a risk of maternal hysterectomy or newborn hypoxic ischemic encephalopathy of 1 in 1250 trials of labor.

Clinical Pearls

See US Preventive Services Task Force Study Quality levels of evidence in Case 1

➤ The best numeric risks for the maternal and fetal outcomes associated with a trial of labor or repeat cesarean section are those from the NICHD MFMU research network prospective cohort study of women with a prior cesarean delivery as depicted in Tables 5–1 and 5–2 (Level II-2).

➤ The best predictor of a successful VBAC is a prior vaginal delivery (Level II-2).

➤ To avoid biased counseling, both absolute and relative risks of a trial of labor versus an elective repeat cesarean should be presented (Level III).

➤ The use of prostaglandins for cervical ripening or induction of labor for women with a prior cesarean section is generally proscribed by current guidance from the American College of Obstetricians and Gynecologists (Level II-B).

REFERENCES

1. National Institutes of Health Consensus Development Conference Statement, Vaginal birth after cesarean: New insights, March 8-10, 2010. Obstet Gynecol 2010;115:1279-1295. 

2. Landon MB, Hauth JC, Leveno KJ, et al. For the National Institute of Child Health and Development Maternal-Fetal Medicine Units Research Network. Maternal and perinatal outcomes associated with a trial of labor after prior cesarean delivery. N Engl J Med. 2004;351:2581-2589. (Level II-2) 

3. Harper LM, Macones GA. Predicting success and reducing the risks when attempting vaginal birth after cesarean. Obstet Gynecol Surv. 2008;63:538-545. (Systematic Review) 

4. Landon MB, Leindecker S, Spong CY, et al. for the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. The MFMU Cesarean Registry: factors affecting the success of trial of labor after previous cesarean delivery. Am J Obstet Gynecol. 2005;193:1016-1023. (Level II-2) 

5. Mercer BM, Gilbert S, Landon MB, et al. for the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Labor outcomes with increasing number of prior vaginal births after cesarean delivery. Obstet Gynecol. 2008;111:285-291. (Level II-2) 

6. Brill Y, Windrim R. Vaginal birth after caesarean section: review of antenatal predictors of success. J Obstet Gynaecol Can. 2003;25:275-286. (Level II-2) 

7. Chauhan SP, Martin JN, Henricks CE, Morrison JC, Magann EF. Maternal and perinatal complications with uterine rupture in 142,075 patients who attempted vaginal birth after cesarean delivery: a review of the literature. Am J Obstet Gynecol. 2003;189:408-417. (Systematic Review) 

8. Smith JG, Mertz HL, Merrill DC. Identifying risk factors for uterine rupture. Clin Perinatol. 2008;35:85-89. (Review) 

9. Cahill AG, Macones GA. Vaginal birth after cesarean delivery: evidence-based practice. Clin Obstet Gynecol. 2007;50:518-525. (Review) 

10. Zelop CM, Shipp TD, Repke JT, Cohen A, Lieberman E. Effect of previous vaginal delivery on the risk of uterine rupture during a subsequent trail of labor. Am J Obstet Gynecol. 2000;183:1184-1186. (Level II-2) 

11. Caughey AB, Shipp TD, Repke JJ, et al. Rate of uterine rupture during a trial of labor in women with one or two prior cesarean deliveries. Am J Obstet Gynecol 1999;181:872-876. 

12. Landon MB, Spong CY, Thom E, et al. Risk of uterine rupture with a trial of labor with multiple and single prior cesarean deliveries. Obstet Gynecol 2006;108:12-20. 

13. Bujold E, Bujold C, Hamilton EF, et al. The impact of a single-layer or double-layer closure on uterine rupture. Am J Obstet Gynecol. 2002;186:1326-1330. (level II-2) 

14. Durnwald C, Mercer B. Uterine rupture, perioperative and perinatal morbidity after single-layer and double-layer closure at cesarean delivery. Am J Obstet Gynecol. 2003;189:925-929. 

15. Gyamfi C, Juhasz G, Gyamfi P, Blumenfeld Y, Stone JL. Single- versus doublelayer uterine incision closure and uterine rupture. J Matern Fetal Neonatal Med. 2006;19:639-643. 

16. Shipp TD, Zelop C, Cohen A, Repke JT, Lieberman E. Post-cesarean delivery fever and uterine rupture in a subsequent trial of labor. Obstet Gynecol. 2003;101:136-139. (Level II-2) 

17. Bujold E, Mehta SH, Bujold C, Gauthier RJ. Interdelivery interval and uterine rupture. Am J Obstet Gynecol. 2002;187:1199-1202. (Level II-2) 

18. Zelop CM, Shipp TD, Repke JT, et al. Outcomes of trial of labor following previous cesarean delivery among women with fetuses weighing > 4000 g. Am J Obstet Gynecol. 2001;185:903-905. (Level II-2) 

19. Lydon-Rochelle M, Holt VL, Easterling TR, Martin DP. Risk of uterine rupture during labor among women with a prior cesarean delivery. New Engl J Med 2001; 345:3-8. 

20. Macones GA, Peipert J, Nelson DB, et al. Maternal complications with vaginal birth after cesarean delivery: a multicenter study. Am J Obstet Gynecol 2005; 193:1656-62. 

21. Sperry JL, Minei JP, Frankel HL, et al. Early use of vasopressors after injury: caution before constriction. J Trauma. 2008;64:9-14. (Level II-1)

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